1. Field of the Invention
The present invention relates to a plug-in coupling for connecting two fluid conduits.
More specifically, the present invention relates to a plug-in coupling for connecting a first fluid conduit to a second fluid conduit, where the first fluid conduit has at least one retaining rib. The plug-in coupling includes a sleeve, which has radial openings. A cylindrical arresting device is axially guided for displacement within the sleeve. The arresting device has axially extending and elastically flexible retaining arms with a hook formed at the free end of the arms for engaging behind the retaining rib of the first fluid conduit when the first fluid conduit is axially introduced into the arresting device. The arms have at their free ends a radially outwardly inclined face, which, when the sleeve and the arresting device are moved axially apart into a locking position, presses against a front edge of one of the radial openings in the sleeve. Thus, the hook more firmly engages with the retaining rib when the arresting device and sleeve move axially away from each other. The arms also have at their free ends a radially inwardly facing inclined face that contacts the retaining rib when the arresting device and sleeve move axially away from each other. In an unlocking position, the arresting device is axially retracted into the sleeve such that the radially outer inclined face is sufficiently spaced from the front edge of the respective one of the radial openings in the sleeve to permit the retaining arms to spread radially apart due to the withdrawal movement of the retaining rib of the first fluid conduit. The arresting device has an unlocking arm disposed between each of the retaining arms. The unlocking arm has a radial outer part that projects radially outwardly, in an axially displaceable manner, through one of the radial openings in the sleeve. At least one sealing ring is disposed between an inner shoulder of the sleeve and the arresting device.
2. Discussion of the Related Art
A plug-in coupling is disclosed by German Reference DE 44 13 346 C1. The sleeve and the arresting or snapping device in the German '346 reference have to be moved axially relatively to one another by hand until the rear contact face of the unlocking arms lies against the rear edge of the respective hole through which the radially outer part of the respective unlocking arm projects outwardly. Without a more detailed explanation, the manner in which the unlocking arms have to be actuated to be moved into this unlocking position is not clear. Therefore, those unfamiliar with these unlocking arms, when attempting to release the coupling (e.g., for the purpose of repairing the device, or devices, connected to the fluid conduits), often only try to press the radially outwardly projecting parts of the unlocking arms radially inwardly, in a futile attempt to decouple the connection.